/*
** $Id: ltm.c,v 2.38.1.1 2017/04/19 17:39:34 roberto Exp $
** Tag methods
** See Copyright Notice in lua.h
*/

#define ltm_c
#define LUA_CORE

#include "lprefix.h"

#include <string.h>

#include "lua.h"

#include "ldebug.h"
#include "ldo.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lvm.h"

static const char udatatypename[] = "userdata";

LUAI_DDEF const char* const luaT_typenames_[LUA_TOTALTAGS] = {
    "no value",
    "nil",
    "boolean",
    udatatypename,
    "number",
    "string",
    "table",
    "function",
    udatatypename,
    "thread",
    "proto" /* this last case is used for tests only */
};

void luaT_init(lua_State* L) {
  // clang-format off
  static const char *const luaT_eventname[] = {  /* ORDER TM */
    "__index", "__newindex",
    "__gc", "__mode", "__len", "__eq",
    "__add", "__sub", "__mul", "__mod", "__pow",
    "__div", "__idiv",
    "__band", "__bor", "__bxor", "__shl", "__shr",
    "__unm", "__bnot", "__lt", "__le",
    "__concat", "__call"
  };
  // clang-format on
  int i;
  for (i = 0; i < TM_N; i++) {
    G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
    luaC_fix(L, obj2gco(G(L)->tmname[i])); /* never collect these names */
  }
}

/*
** function to be used with macro "fasttm": optimized for absence of
** tag methods
*/
const TValue* luaT_gettm(Table* events, TMS event, TString* ename) {
  const TValue* tm = luaH_getshortstr(events, ename);
  lua_assert(event <= TM_EQ);
  if (ttisnil(tm)) { /* no tag method? */
    events->flags |= cast_byte(1u << event); /* cache this fact */
    return NULL;
  } else
    return tm;
}

// get tag method by object, meta method
const TValue* luaT_gettmbyobj(lua_State* L, const TValue* o, TMS event) {
  Table* mt;
  switch (ttnov(o)) {
    case LUA_TTABLE:
      mt = hvalue(o)->metatable;
      break;
    case LUA_TUSERDATA:
      mt = uvalue(o)->metatable;
      break;
    default:
      mt = G(L)->mt[ttnov(o)];
  }
  return (mt ? luaH_getshortstr(mt, G(L)->tmname[event]) : luaO_nilobject);
}

/*
** Return the name of the type of an object. For tables and userdata
** with metatable, use their '__name' metafield, if present.
*/
const char* luaT_objtypename(lua_State* L, const TValue* o) {
  Table* mt;
  if ((ttistable(o) && (mt = hvalue(o)->metatable) != NULL) ||
      (ttisfulluserdata(o) && (mt = uvalue(o)->metatable) != NULL)) {
    const TValue* name = luaH_getshortstr(mt, luaS_new(L, "__name"));
    if (ttisstring(name)) /* is '__name' a string? */
      return getstr(tsvalue(name)); /* use it as type name */
  }
  return ttypename(ttnov(o)); /* else use standard type name */
}

// f: meta method, p1, p2: parament 1 and 2, p3: if has result, for result, else for parament 3
void luaT_callTM(lua_State* L, const TValue* f, const TValue* p1, const TValue* p2, TValue* p3, int hasres) {
  ptrdiff_t result = savestack(L, p3);
  StkId func = L->top;
  setobj2s(L, func, f); /* push function (assume EXTRA_STACK) */
  setobj2s(L, func + 1, p1); /* 1st argument */
  setobj2s(L, func + 2, p2); /* 2nd argument */
  L->top += 3;
  if (!hasres) /* no result? 'p3' is third argument */
    setobj2s(L, L->top++, p3); /* 3rd argument */ // now only for __newindex
  /* metamethod may yield only when called from Lua code */
  if (isLua(L->ci))
    luaD_call(L, func, hasres);
  else
    luaD_callnoyield(L, func, hasres);
  if (hasres) { /* if has result, move it to its place */
    p3 = restorestack(L, result);
    setobjs2s(L, p3, --L->top);
  }
}

int luaT_callbinTM(lua_State* L, const TValue* p1, const TValue* p2, StkId res, TMS event) {
  const TValue* tm = luaT_gettmbyobj(L, p1, event); /* try first operand */
  if (ttisnil(tm))
    tm = luaT_gettmbyobj(L, p2, event); /* try second operand */
  if (ttisnil(tm))
    return 0;
  luaT_callTM(L, tm, p1, p2, res, 1);
  return 1;
}

void luaT_trybinTM(lua_State* L, const TValue* p1, const TValue* p2, StkId res, TMS event) {
  if (!luaT_callbinTM(L, p1, p2, res, event)) {
    switch (event) {
      case TM_CONCAT:
        luaG_concaterror(L, p1, p2);
      /* call never returns, but to avoid warnings: */ /* FALLTHROUGH */
      case TM_BAND:
      case TM_BOR:
      case TM_BXOR:
      case TM_SHL:
      case TM_SHR:
      case TM_BNOT: {
        lua_Number dummy;
        if (tonumber(p1, &dummy) && tonumber(p2, &dummy))
          luaG_tointerror(L, p1, p2);
        else
          luaG_opinterror(L, p1, p2, "perform bitwise operation on");
      }
      /* calls never return, but to avoid warnings: */ /* FALLTHROUGH */
      default:
        luaG_opinterror(L, p1, p2, "perform arithmetic on");
    }
  }
}

int luaT_callorderTM(lua_State* L, const TValue* p1, const TValue* p2, TMS event) {
  if (!luaT_callbinTM(L, p1, p2, L->top, event))
    return -1; /* no metamethod */
  else
    return !l_isfalse(L->top);
}
